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The sensory visual cortex (SVC) is involved in encoding information in visual short-term memory (VSTM). Yet, it remains unclear if the SVC is a necessary component of the brain network necessary for maintaining information in VSTM. The aim of this thesis was to shed light on the debated role of the SVC in VSTM. Thus, I focused on transcranial magnetic stimulation (TMS). TMS uses a coil to transfer electromagnetic stimulation at localized brain areas making the exploration of causal evidence plausible. Through a systematic review and meta-analysis of previous SVC TMS studies I indicated that the SVC is similarly involved in both the encoding and maintenance VSTM phase, and that the controversy was likely due to methodological issues in TMS studies. Building on these findings I conducted two TMS experiments that covered the previous methodological oversights by ensuring the monocular presentation of orientation stimuli. TMS was delivered at different times during the maintenance phase of a delayed change-detection VSTM task, on one side of the occipital hemisphere. Decreased VSTM performance in the ipsilateral occipital hemisphere to visual hemifield, and in the real TMS (compared to sham TMS) condition indicated inhibitory TMS effects, and thus, a causal involvement of the SVC during VSTM maintenance. After establishing the role of the SVC in VSTM maintenance through TMS, I turned to memory load manipulations to further investigate the relationship between short-term memory and perception. I combined short-term memory tasks with perceptual detection tasks, where I manipulated the sensory load of the memory items and measured the effect of this load manipulation on perceptual detection. A combined VSTM and visual perception task provided additional evidence in favor of the sensory recruitment framework, since visual detection was reduced due to the increased VSTM load. Evidence against any cross-modal effects between VSTM and auditory perception was found, and evidence from a combined auditory short-term memory and auditory perception task indicated that sensory recruitment was not supported for the auditory modality. Overall, my findings support the sensory recruitment framework of VSTM, which proposes that sensory visual areas have a dual function: they are involved in the precise sensory encoding of elemental visual features and the short-term maintenance of this information. Member of the committee: Prof. Marios Avraamides, Professor, Department of Psychology, University of Cyprus Member of the committee: Dr. Freek van Ede, Associate Professor, Institute for Brain and Behavior Amsterdam, Department of Experimental and Applied Psychology, Vrije Universiteit Completed

Salience is a core determinant of attentional processing. Although information on salience has been shown to dissipate within a few hundred milliseconds, we recently observed massive effects of salience on the delayed recall from visual working memory (VWM) more than 1300 ms after stimulus onset. Here, we manipulated presentation duration of the memory display and found that effects of salience, albeit decreasing over time, were still markedly present after 3000 ms (2000 ms presentation; Exp. 1). In an attempt to overrule this persistent influence of salience we made less salient stimuli more relevant (by rewarding their prioritized processing in Exp. 2 or by probing them more often in Exp. 3). Participants were unable to reliably prioritize low-salience stimuli. Thus, our results demonstrate that effects of salience or their repercussions have surprisingly long-lasting effects on cognitive performance that reach even relatively late processing stages and are difficult to overrule by volition.

Although the link between developmental dyslexia and visual-spatial deficit has been recurrently highlighted, the relationship between visual-spatial abilities and reading performance is still a co...

It has been established that objects sharing color in a visual display can boost working memory. The capacity to encode singletons particularly benefits from the repetition of colors encoded as perceptual groups. We took profit of existing measures of algorithmic complexity to test whether compressibility could offer a general account of the color-sharing bonus.

Color repetitions in a visual scene boost memory for its elements, a phenomenon known as the color-sharing effect. This may occur because improved perceptual organization reduces information load or because the repetitions capture attention. The implications of these explanations differ drastically for both the theoretical meaning of this effect and its potential value for applications in design of visual materials. If repetitions capture attention to the exclusion of other details, this should be considered when deciding whether to use repetitions in graphic designs. We manipulated the availability of general attention during a visual memory task by comparing groups of participants engaged in meaningless speech or attention-demanding continuous arithmetic. We also tracked eye movements as an implicit indicator of selective attention. Estimated memory capacity was always higher when color duplicates were tested, and under full attention conditions this bonus spilled over to the unique colors too. Analyses of gazes showed that with full attention, participants tended to glance earlier at duplicate colors during stimulus presentation but looked more at unique colors during the retention interval. This pattern of results suggests that the color-sharing bonus occurs because efficient perceptual organization of the display is enhanced by strategic attention allocation when attention is available.

The role of the sensory visual cortex during visual short-term memory (VSTM) remains controversial. This controversy is possibly due to methodological issues in previous attempts to investigate the effects of transcranial magnetic stimulation (TMS) on VSTM. The aim of this study was to use TMS, while covering previous methodological deficits. Sixty-four young adults were recruited to participate in two experiments (Experiment 1: n = 36; Experiment 2: n = 28) using a VSTM orientation change-detection task under TMS. Monocular vision was ensured using red-blue goggles combined with red-blue stimuli. Double-pulse TMS was delivered at different times (Experiment 1: 0, 200 or 1000 ms; Experiment 2: 200, 1000 ms) during a 2 s maintenance phase, on one side of the occipital hemisphere. In Experiment 2, a sham TMS condition was introduced. Decreased detection sensitivity ( d′ ) in the ipsilateral occipital hemisphere to visual hemifield, and in the real TMS (compared with sham TMS) condition indicated inhibitory TMS effects, and thus, a causal involvement of the sensory visual cortex during early (200 ms) and late (1000 ms) maintenance in VSTM. These findings are aligned with sensory recruitment, which proposes that both perceptual and memory processes rely upon the same neural substrates in the sensory visual cortex. The methods used in this study were preregistered and had received in-principle acceptance on 6 June 2022 (Stage 1 protocol can be found in: https://doi.org/10.17605/OSF.IO/EMPDT ).

The present study aims to investigate the role of attention in the allocation of the memory resource described by the continuous-resource model (see Bays, Catalao, & Husain, 2009) and other hybrid "discrete-resource" models, such as the slots+averaging and slots+resources models (see Zhang & Luck, 2008).

The present, pre-registered study is one in a series which aims to determine how the visual short-term memory resource outlined by Bays and colleagues (see e.g., Bays, Catalao, & Husain, 2009; Bays & Husain, 2008; Ma, Husain, & Bays, 2014), is allocated to visual items. Experiments 3a and 3b will be conducted in a confirmatory capacity, building upon initial work conducted by the authors of this pre-registration, with Experiments 3c and 3d aiming to extend these findings.

Examining how saliency modulates encoding of information into visual-working memory

This experiment will explore how attentional control impacts visual short-term memory performance, whilst controlling for cue-switch effects.

In our previous experiments we have demonstrated that saliency has an effect on VWM performance. Saliency was manipulated by presenting target bars of increasing tilt among vertical non-target bars. It was argued that the effect might be due to the more tilted bars better matching the attentional set rather than their higher saliency. To show that this alternative explanation is wrong, we here repeat our task, but this time, on half of the trials, the vertical bars are removed. Thus, instead of presenting tilted bars in a dense array of vertical bars, half of the trials will present only tilted bars. As the non-target bars are crucial for the saliency manipulation, we believe that all three isolated bars are of about equal (relatively high) saliency (while still differentially matching to the attentional set proposed by the alternative explanation). Thus, we predict that the effect of target tilt is strongly reduced (or even completely gone) when the vertical bars are removed and that we replicate our original effect on the trials with vertical bars.

Temporary feature bindings can be learned under specific experimental conditions. However, how this learning occurs and how it is forgotten over long intervals is unclear. We addressed this question with repeated presentation of an array of coloured shapes followed by verbal free recall after delays of one day, one week, and one month. A total of 120 participants viewed 24 repetitions of the same study array of six objects each with two features (shape and colour). After 24 trials, 61 participants reported becoming aware of the repetition while 59 reported being unaware. Memory performance improved across trials, with aware participants showing faster learning than unaware participants whose performance appeared to reflect the capacity of short-term visual memory across all repetitions.Both aware and unaware participants recalled some of the array after their allocated delay, showing that learning had occurred during repetition trials, even for unaware participants who showed little or no improvement across 24 repetition trials. Memory for binding showed no change after one day compared to performance on the 24th repetition trial, was significantly lower for participants tested after one-week, and was lower still for those tested after one-month. Findings are interpreted as consistent with both a short-term, limited capacity visual cache that supports performance during early repetition trials, before learning can have occurred, and gradual strengthening across trials of an episodic long-term memory trace that supports learning. If the episodic trace exceeds the threshold of awareness, this accelerates learning.

In visual working memory (VWM) tasks, participants’ performances can be improved through the use of dimension-based retro-cues, which direct internal attention to prioritize a particular dimension (e.g., color or orientation) of VWM representations even after the stimuli disappear. This phenomenon is known as the dimension-based retro-cue benefit (RCB). The present study investigates whether sustained attention is required for the dimension-based RCB by inserting interference or interruption between the retro-cue and the test array to distract attention. We tested the effects of perceptual interference or cognitive interruption on dimension-based RCB when the interference (Experiments 1 and 2 with masks) or interruption (Experiments 3 and 4 with an odd-even task) occurred concurrently with the stages for the maintenance of prioritized information (long cue-and-interference/interruption interstimulus interval, e.g., Experiments 1 and 3) or the deployment of attention (short cue-and-interference/interruption interstimulus interval, e.g., Experiments 2 and 4). Our results demonstrate that perceptual interference or cognitive interruption attenuates the dimension-based RCB. These findings suggest that sustained attention is necessary for the effective prioritization of a specific dimension of VWM representations. peerReviewed

Object substitution masking (OSM) involves reduced perceptibility by a briefly lingering mask despite no spatial target-mask overlap. Two primary accounts for this phenomenon posit differences in o...

How and what information we store in our Visual Short-Term Memory (VSTM) has been extensively explored, particularly in recent years (e.g., Bundesen, 1987; Schurgin et al., 2020; Zhang & Luck, 2008). Extending Sørensen and Kyllingsbæk (2012) we present a series of behavioural experiments that demonstrate how expertise influences what we see (Experiment 1-3) and in what order it is perceived (Experiment 4). In the first experiment Dall, Watanabe, & Sørensen (2016) examined how expertise influenced VSTM for Japanese Hiragana in participants at different levels of language expertise. Secondly, Dall et al. (2021) studied the relationship between the physical and perceived complexity (Jackson & Raymond, 2005) using Chinese characters and thirdly how stimuli specific expertise influenced both amount encoded and precision of stimuli in VSTM (Dall & Sørensen, 2019). Finally, Experiment 4 explore how expertise affect asynchronously presented stimuli in VSTM (Dall & Sørensen, in press).We find that expertise influences VSTM capacity to the point where it is not influenced by visual complexity, nevertheless it does not seem to influence the precision of representation in VSTM. In addition, we find a bias towards remembering high expertise stimuli when presented alongside low expertise stimuli.

Working memory dysfunction may be central to neurocognitive deficits in schizophrenia. Maintenance of visual information in working memory, or visual short-term memory (vSTM), is linked to general cognitive dysfunction and predicts functional outcome. Lateralized change-detection tasks afford investigation of the contralateral delay activity (CDA), a useful tool for investigating vSTM dysfunction. Previous work suggests "hyperfocusing" of attention in schizophrenia, such that CDA is increased when a single item is maintained in vSTM but reduced for multiple items. If observed early in the disease, vSTM dysfunction may be a key feature of schizophrenia or target for intervention. We investigated CDA during lateralized vSTM of one versus three items using sensor-level electroencephalography and source-level magnetoencephalography in 26 individuals at their first episode of schizophrenia-spectrum psychosis (FESz) and 26 matched healthy controls. FESz were unable to modulate CDA with increased memory load - high-load CDA was reduced and low-load CDA was increased compared to controls. Further, sources of CDA in posterior parietal cortex were reduced in FESz and indices of working memory were correlated with neurocognitive deficits and symptom severity. These results support working memory maintenance dysfunction as a central and early component to the disorder. Targeted intervention focusing on vSTM deficits may be warranted to alleviate downstream effects of this disability.

People maintain object locations not as independent absolute positions but based on inter-object relations in the form of a spatial configuration in visual working memory (VWM). Initial evidence suggests that spatial configurations can be reorganised during maintenance; however, this mechanism is not well understood. We report three experiments investigating this reorganisation process. First, we found that directing spatial attention with a retro cue triggers a reorganisation of spatial configurations during maintenance (Experiment 1). Second, we investigated the role of contextual objects rendered either relevant or irrelevant through the retro cue by manipulating the locations of the context at retrieval both within a partial display (Experiment 2a) and a whole display (Experiment 2b). Whereas the similar impairment of memory performance by changing the relevant and global context suggests a complete reorganisation of spatial configurations in VWM, this interpretation was challenged by the observation of impaired memory performance with changes of the irrelevant objects in a whole display that retains the relevant locations. Thus, we suggest that reorganisation should be considered to be the formation of a partial configuration based on the objects rendered relevant by the retro cue in addition to the originally encoded global configuration, with both configurations affecting memory performance.

Over past decades, converging neuroimaging and electrophysiological findings have suggested a crucial role of posterior parietal cortex (PPC) in supporting the storage capacity of visual short-term memory (VSTM). Moreover, a few recent studies have shown that electrical stimulation over PPC can enhance VSTM capacity, making it a promising method for improving VSTM function. However, the reliability of these results is still in question because null findings have also been observed. Among studies that reported significant effects, some found increased VSTM capacity only in people with low capacity. Here, we hypothesized that subjects' encoding strategy might be a key source of these variable results. To directly test this hypothesis, we stimulated PPC using transcranial direct-current stimulation (tDCS) in male and female human subjects instructed to employ different encoding strategies during a VSTM recall task. We found that VSTM capacity was higher in subjects who were instructed to remember all items in the supra-capacity array of visual stimuli (i.e., the remember-all group), compared to subjects who were told to focus on a subset of these stimuli (i.e., the remember-subset group). As predicted, anodal tDCS over PPC significantly enhanced VSTM capacity only in the remember-subset group, but not in the remember-all group. Additionally, no effect of encoding strategy or its interaction with electrical stimulation was found on VSTM precision. Together, these results suggest that encoding strategy has a selective influence on VSTM capacity and this influence of encoding strategy mediates the effect of electrical stimulation over PPC on VSTM function.

Whether visual short-term memory can be lost over an unfilled delay, in line with time-dependent forgetting, is controversial and prior work has yielded mixed results. The present study explored ti...

Visual working memory (VWM) refers to our ability to selectively maintain visual information in a mental representation. While cognitive limits of VWM greatly influence a variety of mental operations, it remains controversial whether the quantity or quality of representations in mind constrains VWM. Here, we examined behavior-to-brain anatomical relations as well as brain activity to brain anatomy associations with a “neural” marker specific to the retention interval of VWM. Our results consistently indicated that individuals who maintained a larger number of items in VWM tended to have a larger gray matter (GM) volume in their left lateral occipital region. In contrast, individuals with a superior ability to retain with high precision tended to have a larger GM volume in their right parietal lobe. These results indicate that individual differences in quantity and quality of VWM may be associated with regional GM volumes in a dissociable manner, indicating willful integration of information in VWM may recruit separable cortical subsystems.

We investigated limitations in young infants' visual short-term memory (VSTM). We used a one-shot change detection task to ask whether 4- and 8.5-month-old infants (N=59) automatically encode fixated items in VSTM. Our task included trials that consisted of the following sequence: first a brief (500ms) presentation with a sample array of two items, next a brief (300ms) delay period with a blank screen, and finally a test array (2,000ms) identical to the sample array except that the color of one of the two items is changed. In Experiment 1, we induced infants to fixate one item by rotating it during the sample (the other item remained stationary). In Experiment 2, none of the items rotated. In both experiments, 4-month-old infants looked equally at the fixated item when it did and did not change color, providing no evidence that they encoded in VSTM the fixated item. In contrast, 8.5-month-old infants in Experiment 1 preferred the fixated item when it changed color from sample to test. Thus, 4-month-old infants do not appear to automatically encode fixated items in VSTM.

Fabric defect classification is traditionally achieved by human visual examination, which is inefficient and labor-intensive. Therefore, using intelligent and automated methods to solve this problem has become a hot research topic. With the increasing diversity of fabric defects, it is urgent to design effective methods to classify defects with a higher accuracy, which can contribute to ensuring the fabric products' quality. Considering that the fabric defect is not obvious against the texture background and many kinds of them are too confusing to distinguish, a visual long-short-term memory (VLSTM) based integrated CNN model is proposed in this paper. Inspired by the human visual perception and visual memory mechanism, three categories of features are extracted, which are the visual perception (VP) information extracted by stacked convolutional auto-encoders (SCAE), the visual short-term memory (VSTM) information characterized by a shallow convolutional neural network (CNN), and the visual long-term memory (VLTM) information characterized by non-local neural networks. Experimental results on three fabric defect datasets have shown that the proposed model provides competitive results to the current state-of-the-art methods on fabric defect classification.

Numerous studies have shown that more visual features can be stored in visual short-term memory (VSTM) when they are encoded from fewer objects (Luck & Vogel, 1997, Nature, 390, 279-281; Olson & Jiang, 2002, Perception & Psychophysics, 64[7], 1055-1067). This finding has been consistent for simple objects with one surface and one boundary contour, but very few experiments have shown a clear performance benefit when features are organized as multipart objects versus spatially dispersed single-feature objects. Some researchers have suggested multipart object integration is not mandatory because of the potential ambiguity of the display (Balaban & Luria, 2015, Cortex, 26(5), 2093-2104; Luria & Vogel, 2014, Journal of Cognitive Neuroscience, 26[8], 1819-1828). For example, a white bar across the middle of a red circle could be interpreted as two objects, a white bar occluding a red circle, or as a single two-colored object. We explore whether an object benefit can be found by disambiguating the figure-ground organization of multipart objects using a luminance gradient and linear perspective to create the appearance of a unified surface. Also, we investigated memory for objects with a visual feature indicated by a hole, rather than an additional surface on the object. Results indicate the organization of multipart objects can influence VSTM performance, but the effect is driven by how the specific organization allows for use of global ensemble statistics of the memory array rather than a memory benefit for local object representations.

Visual Short-term memory (VSTM) is one of the most crucial processes involved in many cognitive tasks. It is well-established that VSTM in adults can support a limited amount of information. However, this amount can be increased with the help of visuo-spatial attentional cues. In an earlier study, Shimi et al (2014) found that not only adults’ but also children’s VSTM benefited from attentional cues, however, children benefited from these cues to a smaller degree compared to adults, indicating children’s difficulties in orienting attention during the maintenance of information in VSTM. In addition, research showed that adults’ VSTM is higher when participants need to retain familiar items than unfamiliar (Cowan et al., 2015; Ricker & Cowan, 2010). Shimi and Scerif (2015) also found that the familiarity of the item can enhance VSTM in adults and showed further that familiarity can also enhance VSTM in children, yet to a smaller degree, suggesting possible developmental differences in how long-term memory (LTM) may facilitate VSTM. Importantly, they demonstrated that VSTM maintenance is better for cued familiar items for both children and adults, yet children benefitted less from attention cues compared with older individuals, indicating that attentional benefits interact with memoranda familiarity differently across development. Put together, these previous findings suggested that both attentional control and LTM may constrain children’s VSTM compared with older individuals. Therefore, our goal here was to examine further the developmental changes in directing attention within VSTM and the exact role long-term representations may play in these developmental improvements. To investigate this further, we trained 7-year-olds, 11-year-olds, and young adults to associate unfamiliar items (i.e., meaningless shapes) with familiar items (i.e., animals) in order to learn and store new mental representations in LTM. Then, we examined the impact of these newly-formed LTM representations on attentional orienting in service of VSTM performance across different age groups and in comparison with control groups. Results showed that all participants’ VSTM benefitted from attentional cues, however, benefits were smaller for children than for adults. In addition, item familiarity facilitated participants’ performance and cue benefits were larger for familiar than unfamiliar items. Performance was also affected by age, as adults performed better than children. Finally, while adults in the training group performed better than adults in the control group, children’s performance in the two experimental groups did not differ. These age group differences may indicate potential differences in how children use LTM representations to facilitate VSTM. Overall, data from the current thesis are in agreement with previous research in the field that suggests that memoranda characteristics, top-down biases, and storage capacity contribute to developmental differences in VSTM.

Humans have a limited visual short-term memory capacity (K), which is further reduced when processing certain stimuli (e.g., unfamiliar, visually complex, or low discriminability). To examine how these factors influence the bottleneck in attentional and short-term memory, we conducted a series of studies. Experiment 1 (Dall, Watanabe, Sørensen, 2016) examined how expertise modulate K in Japanese hiragana. Experiment 2 (Dall, Wang, Cai, Chan, Sørensen, 2021) divided Chinese characters into four groups based on frequency of use (high vs. low) and stroke count (high vs. low) and how attention is influenced by number of features and stimuli specific expertise. Experiment 3 (Dall, Chan, Sørensen, in review) used colours to examine how stimuli specific expertise influence contentious categories. We extracted attentional components by varying the exposure duration and modelling the data with the Theory of Visual Attention in all three experiments, measuring K and processing speed (C).All three papers showed that stimuli specific expertise improved the K. This increase was unrelated to both stimulus complexity (Experiment 2) and precision of the memory (Experiment 3). Nor did visually complexity influence C of even complex and infrequently Chinese characters (e.g., 鹿), whereas C was modulated by familiarity (Experiment 2).This seems to suggest that the bottleneck in VSTM is influenced by stimuli specific expertise and that this increase cannot be explained as increasing the precision of the stored items.

Visual short-term memory (vSTM) is often measured via continuous-report tasks whereby participants are presented with stimuli that vary along a continuous dimension (e.g., colour) with the goal of memorising the stimulus features. At test, participants are probed to recall the feature value of one of the memoranda in a continuous manner (e.g., by clicking on a colour wheel). The angular deviation between the participant response and the true feature value provides an estimate of recall precision. Two prominent models of performance on such tasks are the two- and three-component mixture models (Bays et al., Journal of Vision, 9(10), Article 7, 2009; Zhang and Luck, Nature, 453(7192), 233–235, 2008). Both models decompose participant responses into probabilistic mixtures of: (1) responses to the true target value based on a noisy memory representation; (2) random guessing when memory fails. In addition, the three-component model proposes (3) responses to a non-target feature value (i.e., binding errors). Here we report the development of mixtur, an open-source package written for the statistical programming language R that facilitates the fitting of the two- and three-component mixture models to continuous report data. We also conduct simulations to develop recommendations for researchers on trial numbers, set sizes, and memoranda similarity, as well as parameter recovery and model recovery. In the Discussion, we discuss how mixtur can be used to fit the slots and the slots-plus-averaging models, as well as how mixtur can be extended to fit explanatory models of visual short-term memory. It is our hope that mixtur will lower the barrier of entry for utilising mixture modelling.

Background/Study Context: Attention can be reflectively oriented to a visual or auditory representation in short-term memory, but it is not clear how aging and hearing acuity affects reflec...

We examined the influence of expansion and contraction on visual short-term memory (VSTM) using a change-detection task. In each trial, several expanding/contracting line segments with various orientations were presented in two successive displays. The orientation of objects in the second display was either identical to, or different from, that of the first display. Observers were asked to judge the presence or absence of an orientation change in successive displays. Results showed that memory performance for expanding objects was higher than for contracting objects (expansion benefit: Experiments 1A and 1B). Further experiments focused on VSTM processing (encoding, storage, and retrieval). Regarding the retrieval stage, an expansion benefit was replicated only when the direction of motion was consistent between two successive displays (Experiment 2A). A cueing stimulus enhanced the memory performance for both expanding and contracting motions and eliminated the expansion benefit (Experiment 2B). Regarding the storage stage, we found the expansion benefit occurred only for shorter blank intervals between the two displays (Experiment 3). Regarding the encoding stage, the expansion benefit was observed regardless of presentation times (Experiment 4). These results indicate the possibility that expanding and contracting motions modulate VSTM.

Background Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Treatments against ALL might lead to later cognitive effects and alterations in brain structure in survivors but to the authors' knowledge the observed variability in the severity of neurocognitive deficits is not fully understood. The objective of the current study was to investigate abnormalities in visual short-term memory (VSTM) brain activation in survivors of childhood ALL using magnetoencephalography. Methods A VSTM task was completed by 40 survivors of ALL and 26 controls. VSTM capacity (Cowan K) and brain activation were assessed during the retention period of the task (400-1400 milliseconds) using a standard minimum norm source localization method. Results Performance (Cowan K) was found to be similar between survivors of ALL and controls. Atypical brain activation was found in survivors of ALL during the task, including overactivation of regions usually involved in VSTM (lateral occipital, precentral gyrus, and postcentral gyrus), recruitment of regions that typically are not involved in VSTM (superior/middle temporal gyrus and supramarginal gyrus), and lower activation of frontal brain regions (inferior frontal gyrus). These patterns of activation were modulated by the age at the time of cancer onset (P = .01) because activity was found to be reduced in participants who were younger at diagnosis. Conclusions The results of the current study suggest a pattern of neural inefficiency and compensatory activity during VSTM in survivors of ALL.

In the theory of visual attention (TVA), it is suggested that objects in a visual scene compete for representation in a visual short-term memory (vSTM) store. The race towards the store is assumed to be biased by top-down controlled weighting of the objects according to their task relevance. Only objects that reach the store before its capacity limitation is reached are represented consciously in a given instant. TVA-based computational modeling of participants' performance in whole- and partial-report tasks permits independent parameters of individual efficiency of top-down control α and vSTM storage capacity K to be extracted. The neural interpretation of the TVA proposes recurrent loops between the posterior thalamus and posterior visual cortices to be relevant for generating attentional weights for competing objects and for maintaining selected objects in vSTM. Accordingly, we tested whether structural connectivity between posterior thalamus and occipital cortices (PT-OC) is associated with estimates of top-down control and vSTM capacity. We applied whole- and partial-report tasks and probabilistic tractography in a sample of 37 healthy adults. We found vSTM capacity K to be associated with left PT-OC structural connectivity and a trend-wise relation between top-down control α and right PT-OC structural connectivity. These findings support the assumption of the relevance of thalamic structures and their connections to visual cortex for top-down control and vSTM capacity.

Mainstream theories of visual short-term memory (VSTM) posit that VSTM consists of a single, limited capacity store (e.g., Luck & Vogel, 2013). Recently, however, some researchers (Sligte, Scholte & Lamme, 2008; van Moorselaar et al., 2015; Vandenbroucke et al., 2015) have proposed that VSTM consists of two separate components, a limited capacity (3–4 item) durable store and a fragile, high-capacity (5–7 item) store. To assess the structure of VSTM, these authors used a change detection task that required participants to compare two arrays (a memory array and a test array) separated by a brief temporal interval. Critically, these researchers compared performance under conditions when a cue was shown prior to the test array (retro-cue), or after the test array was shown (post-cue). They reported that participants could recall at least twice as many items in the retro-cue condition as in the post-cue condition and interpreted this as evidence for the existence of an initial stage of VSTM with a much higher capacity than was previously thought. The view that VSTM may consist of two distinct stores challenges decades of evidence and theory on the structure of VSTM. In the current study, we directly examined the architecture of VSTM using state-trace analysis, a direct method for assessing the dimensionality of psychological constructs. We replicated the benefit of presenting retro- versus post-cues on memory. However, the results of the state-trace analysis were consistent with a single store model of VSTM. We conclude that the improvement in performance in the retro-cue condition reflects increased attentional processing of the probed item rather than a distinct memory store.

After viewing a series of sequentially presented visual stimuli, subjects can readily generate mean representations of various visual features. Although these average representations seem to be formed effortlessly and obligatorily, it is unclear how such averages are actually computed. According to conventional prototype models, the computation entails an equally weighted average taken over all the stimuli. To test this hypothesis, we had subjects estimate the running averages of some feature in a series of sequentially presented stimuli. Part way through the series, we perturbed the distribution from which stimuli were drawn, which allowed us to test alternative models of the computations behind subjects' estimates. In both explanatory and predictive tests, a model in which the most recent items had disproportionate high weight outperformed a model in which all items carried equal weight. Such recency-weighted behavior was shown consistently in multiple experiments in which subjects estimated running averages of length of vertical lines. However, the degree to which recent items were prioritized varied with the type of stimulus, such that when estimating the running averages of a series of numerals, subjects showed less recency prioritization. We conclude that previous evaluations of prototype models have made unrealistic assumptions about the nature of a prototype, and that a reassessment of prototype models of visual memory and perceptual categorization may be in order.

In a seminal study, Yoon, Johnson and Csibra [PNAS, 105, 36 (2008)] showed that nine-month-old infants retained qualitatively different information about novel objects in communicative and non-communicative contexts. In a communicative context, the infants encoded the identity of novel objects at the expense of encoding their location, which was preferentially retained in non-communicative contexts. This result had not yet been replicated. Here we attempted two replications, while also including a measure of eye-tracking to obtain more detail of infants' attention allocation during stimulus presentation. Experiment 1 was designed following the methods described in the original paper. After discussion with one of the original authors, some key changes were made to the methodology in Experiment 2. Neither experiment replicated the results of the original study, with Bayes Factor Analysis suggesting moderate support for the null hypothesis. Both experiments found differential attention allocation in communicative and non-communicative contexts, with more looking to the face in communicative than non-communicative contexts, and more looking to the hand in non-communicative than communicative contexts. High and low level accounts of these attentional differences are discussed. [Abstract copyright: Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.]

I address a recent extension of the generalized context model (GCM), a model which excludes prototypes, to the visual short-term memory (VSTM) literature, which is currently deluged with prototype effects. The paper includes a brief review whose aim is to discuss the background and key findings suggesting that prototypes have an obligatory influence on visual short-term memory responses in the same VSTM task that the GCM's random walk extension, EBRW, was extended to account for: Sternberg scanning. I present a new model that incorporates such "central tendency representations" in memory, as well as several other regularities of the literature, and compare its prediction and postdictions to those of the GCM on some unpublished Sternberg scanning data. The GCM cannot account for the pattern in those data without post hoc modifications but the pattern is predicted nicely by the central tendency representation model. Although the new model is certainly wrong, the review and modeling exercise suggest a reconsideration of prototype models may be warranted, at least in the VSTM literature.

The present studies explored how performance in multidimensional displays varies as a function of visual working memory load, item distribution across depths, and individual capacity differences. In Experiment 1, the benefit of depth information (one depth vs. two depths) was examined across seven set sizes within a change-detection paradigm. Multiple depth planes engendered performance benefits with five items, but elicited performance decrements with three items. These effects were associated with working memory capacity, such that benefits were only observed when the working memory load exceeded an individual's max capacity. Experiment 2 evaluated how the distribution of items in depth aids working memory performance. Equal distribution of items across depths produced higher accuracy compared with when the target was isolated in depth. Lastly, Experiment 3 explored how differences in working memory capacity affect an individual's ability to use depth information to improve their performance. The results indicate that both low-capacity and high-capacity individuals can benefit from depth information, but this may vary as a function of working memory load. Overall, the results indicate that multidimensional displays can improve performance with sufficient working memory load, possibly through some sort of depth tag.

Our study aimed to examine the effects of pattern complexity on visual short-term memory (VSTM) at the retrieval stage in typical developing adults with different autism spectrum quotient (AQ) scores. Participants underwent electroencephalography during a same-different task, in which they judged as rapidly and accurately as possible whether the target pattern (S1) was the same or different from the comparison pattern (S2). In the same-different task, pattern complexity (simple and complex patterns) was manipulated. We analyzed two peaks of waveforms (P3b and positive slow wave [PSW]) elicited by S2 and compared them between the high and low AQ groups (each n = 11). The PSW amplitude was greater in the high AQ group than those in the low AQ group (p

Recently, subways have become an important part of public transportation and have developed rapidly in China. In the subway station setting, pedestrians mainly rely on visual short-term memory to obtain information on how to travel. This research aimed to explore the short-term memory capacities and the difference in short-term memory for different information for Chinese passengers regarding subway signs. Previous research has shown that people’s general short-term memory capacity is approximately four objects and that, the more complex the information, the lower people’s memory capacity. However, research on the short-term memory characteristics of pedestrians for subway signs is scarce. Hence, based on the STM theory and using 32 subway signs as stimuli, we recruited 120 subjects to conduct a cognitive test. The results showed that passengers had a different memory accuracy for different types of information in the signs. They were more accurate regarding line number and arrow, followed by location/text information, logos, and orientation. Meanwhile, information type, quantity, and complexity had significant effects on pedestrians’ short-term memory capacity. Finally, according to our results that outline the characteristics of short-term memory for subway signs, we put forward some suggestions for subway signs. The findings will be effective in helping designers and managers improve the quality of subway station services as well as promoting the development of pedestrian traffic in such a setting.

Signal transmission in the brain propagates via distinct oscillatory frequency bands but the aperiodic component, 1/f activity, almost always co-exists which most of the previous studies have not sufficiently taken into consideration. We used a recently proposed parameterization model that delimits the oscillatory and aperiodic components of neural dynamics on lifespan aging data collected from human participants using magnetoencephalography (MEG). Since healthy aging underlines an enormous change in local tissue properties, any systematic relationship of 1/f activity would highlight their impact on the self-organized critical functional states. Furthermore, we have used patterns of correlation between aperiodic background and metrics of behavior to understand the domain general effects of 1/f activity. We suggest that age-associated global change in 1/f baseline alters the functional critical states of the brain affecting the global information processing impacting critically all aspects of cognition, e.g., metacognitive awareness, speed of retrieval of memory, cognitive load, and accuracy of recall through adult lifespan. This alteration in 1/f crucially impacts the oscillatory features peak frequency (PF) and band power ratio, which relates to more local processing and selective functional aspects of cognitive processing during the visual short-term memory (VSTM) task. In summary, this study leveraging on big lifespan data for the first time tracks the cross-sectional lifespan-associated periodic and aperiodic dynamical changes in the resting state to demonstrate how normative patterns of 1/f activity, PF, and band ratio (BR) measures provide distinct functional insights about the cognitive decline through adult lifespan.

To understand more naturalistic visual cognition, a growing body of research has investigated how pre-existing long-term memory (LTM) influences representations and processes actively engaged in visual short-term memory (VSTM). Prior research on LTM and the representation aspect of VSTM, such as the number of retained VSTM items or VSTM storage capacity, has yielded mixed findings. However, converging evidence from different experimental approaches suggests that pre-existing LTM reliably modulates the initial process of transferring fragile sensory inputs into durable VSTM contents. Here, we review recent findings along this line of research and discuss potential mechanisms for future investigations. We find that pre-existing facilitates the formation of VSTM even though it may not replace the limited VSTM storage capacity. These findings, therefore, highlight the importance of assessing how pre-existing LTM affects the mental processes underlying naturalistic visual cognition.

It has been established that objects sharing color in a visual display can boost working memory. The capacity to encode singletons particularly benefits from the repetition of colors encoded as perceptual groups. We manipulated the algorithmic complexity of visual displays to test whether compressibility of information could account for the color-sharing bonus. This study used a free recall working memory task in which the participants were shown displays of 2 to 8 color items. We examined the influence of set size, complexity, number of same-color clusters and amount of color redundancy. The results showed that the probability of correct recall of the pattern and the proportion of similarity between the pattern and the response decreased with an increase of each manipulated variable, except for color redundancy in terms of probability of correct recall. The model performance of complexity did not differ from that of clusters, but complexity was found more accurate than either set size or color redundancy. The results also showed that similar items were more often recalled adjacently, and complexity correlated strongly with the number of extra color repetitions in the response, suggesting that more complex patterns encouraged the use of information compression. Moreover, color repetitions were more often recalled first and the probability of correct recall for singletons and sub-patterns could be predicted by the compressibility measure. We discuss the potential advantage of using compressibility measures to capture the effects of regularities in visual patterns, in particular to refine analysis of the color-sharing bonus.

The basis of visual short-term memory (VSTM) impairments in preclinical Alzheimer’s disease (AD) remains unclear. Research suggests that eye movements may serve as indirect surrogates to investigate VSTM. Yet, investigations in preclinical populations are lacking. Fifty-two individuals from a familial Alzheimer’s disease (FAD) cohort (9 symptomatic carriers, 17 presymptomatic carriers and 26 controls) completed the “Object-localisation” VSTM task while an eye-tracker recorded eye movements during the stimulus presentation. VSTM function and oculomotor performance were compared between groups and their association during encoding investigated. Compared to controls, symptomatic FAD carriers showed eye movement patterns suggestive of an ineffective encoding and presymptomatic FAD carriers within 6 years of their expected age at symptom onset, were more reliant on the stimuli fixation time to achieve accuracy in the localisation of the target. Consequently, for shorter fixation times on the stimuli, presymptomatic carriers were less accurate at localising the target than controls. By contrast, the only deficits detected on behavioural VSTM function was in symptomatic individuals. Our findings provide novel evidence that encoding processes may be vulnerable and weakened in presymptomatic FAD carriers, most prominently for spatial memory, suggesting a possible explanation for the subtle VSTM impairments observed in the preclinical stages of AD.

Limitations in the ability to temporarily represent information in visual working memory (VWM) are crucial for visual cognition. Whether VWM processing is dependent on an object’s saliency (i.e., how much it stands out) has been neglected in VWM research. Therefore, we developed a novel VWM task that allows direct control over saliency. In three experiments with this task (on 10, 31, and 60 adults, respectively), we consistently found that VWM performance is strongly and parametrically influenced by saliency and that both an object’s relative saliency (compared with concurrently presented objects) and absolute saliency influence VWM processing. We also demonstrated that this effect is indeed due to bottom-up saliency rather than differential fit between each object and the top-down attentional template. A simple computational model assuming that VWM performance is determined by the weighted sum of absolute and relative saliency accounts well for the observed data patterns.

Visual short-term memory (VSTM) links perception with higher cognitive processes by maintaining visual information that is absent from the environment. Yet, it remains unclear if sensory visual cortex is a necessary component of the brain network that underlies short-term maintenance of visual information. Previous reviews remain inconclusive and open to interpretation. Here, we aimed to systematically identify and review studies that have investigated the role of the sensory visual cortex in VSTM using transcranial magnetic stimulation (TMS), a method that allows exploration of causal relationships, and to quantitatively explore the effect of TMS interference on the sensory visual cortex during VSTM using meta-analytic methodology. Thirteen studies were identified and qualitatively reviewed. Out of those, seven studies provided sufficient statistical data for meta-analysis and yielded a total of 30 effect sizes, which were included in the meta-analyses. Two meta-analyses were conducted, one regarding the encoding phase of VSTM (19 effect sizes), and one regarding the maintenance phase of VSTM (11 effect sizes). The results from the systematic review and the two meta-analyses indicate that the sensory visual cortex is likely involved in both the encoding and maintenance phase of VSTM. In some cases, evidence did not show significant effects of TMS, however, this is suggested to be due to low memory load or low perceptual task demands. Overall, these findings support the idea that sensory visual areas are part of the brain network responsible for successfully maintaining information in short-term memory when no physical stimulus is present in the environment.

We investigated the role of the human medio-temporal complex (hMT+) in the memory encoding and storage of a sequence of four coherently moving random dot kinematograms (RDKs), by applying repetitive transcranial magnetic stimulation (rTMS) during an early or late phase of the retention interval. Moreover, in a second experiment, we also tested whether disrupting the functional integrity of hMT+ during the early phase impaired the precision of the encoded motion directions. Overall, results showed that both recognition accuracy and precision were worse in middle serial positions, suggesting the occurrence of primacy and recency effects. We found that rTMS delivered during the early (but not the late) phase of the retention interval was able to impair not only recognition of RDKs, but also the precision of the retained motion direction. However, such impairment occurred only for RDKs presented in middle positions along the presented sequence, where performance was already closer to chance level. Altogether these findings suggest an involvement of hMT+ in the memory encoding of visual motion direction. Given that both position sequence and rTMS modulated not only recognition but also the precision of the stored information, these findings are in support of a model of visual short-term memory with a variable resolution of each stored item, consistent with the assigned amount of memory resources, and that such item-specific memory resolution is supported by the functional integrity of area hMT+.

Several studies have shown enhanced performance in change detection tasks when spatial cues indicating the probe’s location are presented after the memory array has disappeared (i.e., retro-cues) compared with spatial cues that are presented simultaneously with the test array (i.e., post-cues). This retro-cue benefit led some authors to propose the existence of two different stores of visual short-term memory: a weak but high-capacity store (fragile memory (FM)) linked to the effect of retro-cues and a robust but low-capacity store (working memory (WM)) linked to the effect of post-cues. The former is thought to be an attention-free system, whereas the latter would strictly depend on selective attention. Nonetheless, this dissociation is under debate, and several authors do not consider retro-cues as a proxy to measure the existence of an independent memory system (e.g., FM).We approached this controversial issue by altering the attention-related functions in the right superior parietal lobule (SPL) by transcranial magnetic stimulation (TMS), whose effects were mediated by the integrity of the right superior longitudinal fasciculus (SLF). Specifically, we asked whether TMS on the SPL affected the performance of retro cues vs. post-cues to a similar extent. The results showed that TMS on the SPL, mediated by right SLF-III integrity, produced a modulation of the retro-cue benefit, namely a memory capacity decrease in the post-cues but not in the retro-cues. These findings have strong implications for the debate on the existence of independent stages of visual short-term memory and for the growing literature showing a key role of the SLF for explaining the variability of TMS effects across participants., Spanish Ministry of Economy and Competitiveness, European Commission PSI2015-73503-JIN

Visual short-term memory (VSTM) enables humans to form a stable and coherent representation of the external world. However, the nature and temporal dynamics of the neural representations in VSTM that support this stability are barely understood. Here we combined human intracranial electroencephalography (iEEG) recordings with analyses using deep neural networks and semantic models to probe the representational format and temporal dynamics of information in VSTM. We found clear evidence that VSTM maintenance occurred in two distinct representational formats which originated from different encoding periods. The first format derived from an early encoding period (250 to 770 ms) corresponded to higher-order visual representations. The second format originated from a late encoding period (1,000 to 1,980 ms) and contained abstract semantic representations. These representational formats were overall stable during maintenance, with no consistent transformation across time. Nevertheless, maintenance of both representational formats showed substantial arrhythmic fluctuations, i.e., waxing and waning in irregular intervals. The increases of the maintained representational formats were specific to the phases of hippocampal low-frequency activity. Our results demonstrate that human VSTM simultaneously maintains representations at different levels of processing, from higher-order visual information to abstract semantic representations, which are stably maintained via coupling to hippocampal low-frequency activity.

Visual short-term memory (VSTM) deficits including VSTM binding have been associated with Alzheimer's disease (AD) from preclinical to dementia stages, cross-sectionally. Yet, longitudinal investigations are lacking. The objective of this study was to evaluate VSTM function longitudinally and in relation to expected symptom onset in a cohort of familial Alzheimer's disease. Ninety-nine individuals (23 presymptomatic; 9 symptomatic and 67 controls) were included in an extension cross-sectional study and a sub-sample of 48 (23 presymptomatic carriers, 6 symptomatic and 19 controls), attending two to five visits with a median interval of 1.3 years, included in the longitudinal study. Participants completed the “What was where?” relational binding task (which measures memory for object identification, localisation and object-location binding under different conditions of memory load and delay), neuropsychology assessments and genetic testing. Compared to controls, presymptomatic carriers within 8.5 years of estimated symptom onset showed a faster rate of decline in localisation performance in long-delay conditions (4s) and in traditional neuropsychology measures of verbal episodic memory. This study represents the first longitudinal VSTM investigation and shows that changes in memory resolution may be sensitive to tracking cognitive decline in preclinical AD at least as early as changes in the more traditional verbal episodic memory tasks., Highlights • VSTM function was investigated in presymptomatic and symptomatic FAD carriers. • PMCs showed faster decline in VSTM function (target localisation) than controls. • Target localisation accuracy decreased with proximity to expected symptom onset. • “What was where?” may be sensitive to tracking preclinical cognitive decline.

Although recent evidence suggests that visual short-term memory (VSTM) is a continuous resource, little is known about how flexibly this resource can be allocated. Previous studies using probabilistic cues to indicate two different levels of probe probability have found that response precision can be predicted according to a continuous allocation of resources that depends on attentional priority. The current study used a continuous report procedure and attentional prioritization via simultaneous probabilistic spatial cues to address whether participants can use up to three levels of attentional priority to allocate VSTM resources. Three experiments were performed with differing priority levels, different cues, and cue presentation time. Although group level analysis demonstrated flexible allocation, there was limited evidence that participants were using three priority levels. An individual differences approach revealed that a minority of participants were using three levels of attentional priority, demonstrating that, while possible, it is not the predominant pattern of behavior.